Decorated active-intelligent film using urea and fish gelatin quantum dots for improving and detecting the quality of chilled trout fillets

Abstract

In this study, an active-intelligent film was created by adding urea and fish gelatin quantum dots along with the mucilage, aiming at improving and monitoring the microbial and chemical quality of trout fillets during chilled storage. Fish gelatin and urea quantum dots were successfully synthesized using microwave and low-heat methods. Enriching the alginate film to quantum dots and mucilage resulted in superior mechanical characteristic including thickness (0.0061 ± 0.072 mm), tensile strength (62.8 ± 1.41%), and elongation (35 ± 1.04%) while decreasing some physical properties like solubility (73 ± 5.14%) and water vapor permeability (1.1 ± 0.49 g/m− 2 s− 1). Treatments containing quantum dots indicated inferior transparency and an excellent ability in blocking UV light. The FTIR functional groups proved the presence of film compounds. An uneven surface and weaker crystallinity structure were observed in treatments containing mucilage, recorded by FESEM and XRD. Adding gelatin quantum dots and mucilage led to the lowest level of total (8.4 ± 1 CFU/g− 1), psychrophilic (5.4 ± 1 CFU/g− 1), and H2S-producing (7 ± 1 CFU/g− 1) bacteria after 16 days. Additionally, the lowest level of pH (7.7 ± 0.09), TVB-N (76.6 ± 0.47%), PV (7.48 ± 0.68%), TBA (0.94 ± 0.06), and FFA (1.13 ± 0.004%) were observed in gelatin quantum dots and mucilage contained treatment. After 8 days, the fluorescence intensity of films enhanced due to the increasing level of bacteria. The changes in microbial and chemical indexes were perfectly detected by increasing the fluorescence and color changes of produced films. The active-intelligent films are introduced as a novel potential packaging for prolonging the shelf life along with monitoring the freshness of food.